It’s back with a bang. After nearly two years in orbit, the Air Force’s secretive X37-B space plane touched down at Florida’s Kennedy Space Center yesterday, reportedly waking up nearby residents with a sonic boom. The space drone’s 719-day trip was the longest of the program’s four missions. Military personnel say the X37-B has been testing space’s effects on various material samples and reporting on the performance of a new thruster system designed for advanced satellites. A fifth mission launches later this year.